There are many important unanswered questions regarding the best methods to improve outcome in infants and children following cardiopulmonary arrest (CPA). There is also a need to identify reliable indicators of poor outcome/vegetative state in CPA survivors to help families make informed decisions and reduce potential life-long burdens on the family and healthcare system. The primary aim of this clinical trial planning grant is to organize an effective research team and develop the elements essential for conducting successful clinical trials of pediatric CPA. This planning grant will develop a clinical trial to assess (1) the effect of early mild therapeutic hypothermia on survival and functional outcome following pediatric CPA; (2) identify early clinical signs and biomarkers associated with survival and various degrees of functional outcome following CPA; and (3) establish the changes in functional outcome over time in children following CPA using more precise outcome measurement tools than previously employed. The latter goal will establish the basis for subsequent trials evaluating the effectiveness of different rehabilitative interventions on ultimate outcome. This planning grant will (1) identify additional collaborators, (2a) develop the experimental design and (2b) intervention protocols including treatment protocols for managing the patient following CPA, (3) select and establish neurological, biomarker, comorbid and functional outcome measurement data elements and tools, (4a) determine the effect size and power needed for clinically meaningful results and (4b) establish an analysis plan including a safety monitoring board, (5) develop a data coordination/management team, (6) assess the feasibility of subject recruitment strategies, (7a) identify the obstacles to conducting a randomized intervention trial waiving informed consent and (7b) determine the requirements that sites need to meet, (8) select study exclusion and inclusion criteria, (9) develop a training program to assure that the treatment intervention and overall patient care is replicated across sites, (10) select sites for the hypothermia randomized controlled trial (RCT) and obtain Institutional Review Board approval, and (11) develop administrative operations to manage the RCT. The long-term objective is to utilize the clinical trial network to conduct additional trials so as to advance the science of pediatric resuscitation.